Acceleration switch



Aug. 11, 1964 PINO 3,144,528

ACCELERATION SWITCH Filed March 29, 1961 INVENTOR L one/s HA/a BY Maw,(04., M mwm ATTORNEYS United States Patent Office 3,144,528 PatentedAug. 11, 1964 3,144,528 I ACCELERATION SWITCH Louis Pino, Rego Park,N.Y., assignor toLeesona Corporation, Cranstou, R.I., a corporation ofMassachusetts Filed Mar. 29, 1961, Ser. No. 99,232 4 Claims. (Cl.20tl61.45)

This invention relates to an electrical switch, and more particularly,to an electrical switch which operates in response to accelerationforces.

Acceleration switches are well-known in the art. However, the prior artdevices are subject to certain disadvantages. For example, it isdifficult to make an adjustable acceleration responsive switch. Further,the prior art devices are subject to creeping action when subjected tovibration, which disadvantage precludes their use in certaininstallations.

Accordingly, it is an object of this invention to provide an improvedelectrical switch which is responsive to forces of acceleration.

It is another object of this invention to provide an adjustableelectrical switch which operates in response to forces of acceleration.

It is a further object of this invention to provide an accelerationresponsive switch which is simple in construction, easy to manufacture,and easy to adjust.

It is another object of this invention to provide an accelerationresponsive electrical switch with a minimum of moving elements in whichthe primary element is purely rotational and is supported by bearingssuch that no creeping action of the switch components can occur whensubjected to vibration.

It is another object of this invention to provide an improvedacceleration switch which is encased in a sealed container with dampingfluid, which switch when subjected to vibration experiences an effectivedamping action from the onset of angular movement of the accelerationresponsive element, which damping action continues until the switchoperation is completed.

Briefly, in accordance with one illustrative embodiment of thisinvention, an eccentric mass is mounted on a shaft and the shaft isjournaled in one or more suitable bearings in a switch housing. Anelongated substantially flat spring member, which may be in the form ofa wire, is secured at its midpoint to the shaft to form a dualcantilever beam assembly. Advantageously, a pair of adjusting setscrewsare providing in the housing in positions to engage portions of theeccentric mass and thus limit the arc of rotation of the eccentric mass.Also advantageously, a pair of adjustable insulating supports areprovided in the regions of the ends of the spring member, whichinsulating supports have mounted thereon, suitable electrical contactpins. Preferably, the supports are rotatably mounted with their axes ofrotation perpendicular to the plane of movement of the flat springmember. Advantageously, the contacts are mounted eccentrically on thesupports such that rotation of the supports about their axes controlsthe positionof the contacts relative to opposite ends of the springmember. With this simple arrangement, both contacts can be moved intoengagement with the spring member on'the same side of the spring memberto define a normally closed switch. This embodiment is opened by theapplication of acceleration forces to the eccentric mass. These forcescause the mass to rotate, developing a torque which produces a stress inthat portion of the spring member between the shaft and the one contacttowards which the eccentric mass is rotating, which torque moves theopposite end of the spring member away from the other contact pin.

In another illustrative embodiment, the ends of the spring member may beplaced on opposite sides of the 2 respective contact pins by bending thespring and/or rotation of the pin supports. In this embodiment, theswitch will be normally open and in response to acceleration of theswitch housing, the eccentric mass will rotate toward the one contactwhich normally engages the spring member, thereby developing a torquewhich produces a stress in one part of the spring which moves the otherpart of the spring into engagement with the other contact pin.

Advantageously, in either of these embodiments, the cantilever beamspring, or wire, determines the range of adjustments available todetermine the magnitude of the forces required to actuate the switch.Within this range, the adjustment of the switch is achieved bypositioning the switch contacts relative to the spring beam. Alsoadvantageously, the entire switch assembly is hermetically sealed in acontainer which is filled with damping fluid to provide a damping actionwith respect to vibration.

These and various other objects and features of the invention will bemore clearly understood from a reading of the detailed specification inconjunction with the drawing, in which:

FIGURE 1 is a side view in elevation of one illustrative embodiment ofthis invention with the cover removed;

FIGURE 2 is a View of FIGURE 1 taken in the direction of the arrow 2with the side of the cover removed;

FIGURES 3 and 4 are side views in elevation of an embodiment of theinvention which defines a normally closed switch and is shown in FIGURE3 in its normal position and in FIGURE 4 in its operated position; and

FIGURES 5 and 6 show another illustrative embodiment of this inventionwhich operates as a normally open switch, shown in FIGURE 5 in itsnormal position, and in FIGURE 6 in its actuated position.

Referring now to FIGURES 1 and 2, there is depicted one illustrativeembodiment of this invention in which a housing 10 contains a suitablesupport member 12. The entire housing 10 is preferably hermeticallysealed by a metal cover 13, shown in FIGURE 2, and contains a suitablenonconducting damping fluid. This damping fluid will damp out anyexternally applied vibrations which would otherwise prevent properswitch operation. Advantageously, this damping action will be continuousthroughout the operation of the switch. A journal bearing 14 is mountedin the support member 12 and a shaft 16 is rotatably mounted in thebearing 14. An eccentric mass 18 is secured to the shaft 16 and thiseccentric mass is advantageously in the form of a sector of a circle;for example, a semicircle. A pair of setscrews 20 and 22 are supportedin suitable supports 24 and 26 respectively, on the support member 12.These setscrews are positioned so that their ends engage flat surfaceson opposite sides of the eccentric mass 18 and thus their adjustmentcontrols the are through which the eccentric mass 18 may rotate. A dualcantilever beam spring 28 is preferably, though not necessarily, securedat its midpoint to shaft 16. Advantageously, this spring may be a wireof suitable diameter or it may be a flat spring having a relativelyrectangular cross section, depending on the particular range of forcesto which the switch is to be adjustable.

A pair of insulating supports 30 and 32 are rotatably mounted in supportmember 12 and these supports have switch contacts 34 and 36respectively, mounted thereon. As best seen in FIGURE 2, the axes ofsupports 30 and 32 are perpendicular to the plane of movement of theeccentric mass 18. Thus the switch contacts 34 and 36 which areeccentricaly mounted on supports 30 and 32 respectively, may bepositioned relative to the spring 28 by rotation of the members 30 and32. Suitable conductors, not shown, may be connected to contacts 34 and36 to connect the switch in the circuit to be controlled.

FIGURES 3 and 4 show side elevational views of an embodiment of thisinvention with the cover removed,

which embodiment is adjusted to operate as a normally closed switch, itsnormal position being shown in FIG- URE 3 and its operated positionbeing shown in FIG- URE 4. As best seen in FIGURE 3, opposite ends ofspring 28 are in contact with contacts 34 and 36. The eccentric mass 18is in engagement with setscrews 20 while setscrews 22 is displaced fromthe flat surface of the mass 18. It is apparent that contacts 34 and 36are exerting considerable stress on the spring 28 to produce thecurvature in the spring 28, shown in FIGURE 3. When the embodiment ofFIGURE 3 is subjected to any force of acceleration in the direction ofarrow 40 in FIGURE 4, the eccentric mass or sector 18 will tend torotate its axle 16 and move until sector 18 engages setscrew 22. Thisrotation of sector 18 develops a stress in spring 28 between the axle 16and the contact pin 36. This stress will oppose the acceleration forceapplied to the mass 18. When a sufficient accelerating force is appliedto the mass 18, it rotates to the position shown in FIGURE 4, in whichposition the spring 28 has moved away. from contact 34, thus opening theswitch. The particular force required to open the electrical circuitbetween pin 34 and pin 36 will be determined for a given spring by thepositions of pins 34 and 36, which positions may advantageously beadjusted by rotating the contact pin support members 30 and 32respectively, by any convenient means, not shown.

FIGURES and 6 show another illustrative embodiment of this invention inside elevation, which embodiment acts as a normally open switch and isshown in its normal position in FIGURE 5 and in its actuated positioninFIGURE 6. The principal'distinction between the normally open embodimentof FIGURE 5 and the normally. closed embodiment of FIGURE 3 is theposition of spring 28 relative to pin 34. In FIGURE 3, the spring is tothe right of pin 34and in engagement with the pin,

While in FIGURE 5, the spring 28 is to the left of pin 34 and out ofcontact with this pin. When the embodiment of FIGURES 5 and 6 issubjected to an accelerating force in the direction of arrow 42 inFIGURE 6, the eccentric mass 18 will tend to rotate in the direction ofarrow 43 and thus develop a stress in spring 28 between the axle 16 andcontact pin 36. This stress will continue to develop to the limit of theapplied force of acceleration or until the mass 18 engages the end ofsetscrew 22, whichever is first. Assuming that a suflicient acceleratingforce is applied to the switch, torque will be applied to the spring 28until it engages contact pin 34 and thus completes the electricalcircuit between contact pin 34 and contact pin 36. When the acceleratingforce is removed in each of the embodiments shown in FIGURES 4 and 6,the switch will return to its respective normal position as shown inFIGURES 3 and 5.

While I have shown and described certain illustrative embodiments ofthis invention, it is understood that the principles thereof may beapplied to other embodiments without departing from the spirit and scopeof this inven tion. For example, in FIGURE 3, the positions of the endsof spring 28 relative to contact pins 34 and 36, may be reversed and theswitch will nevertheless open in re sponse to an accelerating force. Forexample, if the spring 28 in FIGURE 3 were placed on the opposite sides4 of the pins 34 and 36, the switch would be normally closed and theswitch would open at the point of contact between spring 28 and contactpin 36 in response to the acceleration forces in the direction of arrow40 in FIG- URE 4.

What is claimed is:

1. An acceleration responsive electrical switch comprising a supportmember, a shaft rotatably mounted in said support member, an eccentricmass secured to said shaft, means normally maintaining said eccentricmass to one side of said shaft relative to the direction of the force ofacceleration to be measured, said last-mentioned means including meansfor limiting the arc of rotation of said mass, spring means secured tosaid shaft and extending radially from said shaft, and contact meanspositioned in the path of said spring means to be engaged thereby duringthe rotation of said mass in response to an accelerating force.

2. A switch according to claim 1, wherein the contact means comprisingone contact eccentrically mounted on a rotatably shaft, and the positionof said contact means is adjustable relative to said spring means byrotating the shaft to determine the magnitude of acceleration forcerequired to actuate said switch.

3. A switch according toclaim 1, wherein said contact means include apair of contacts mounted on a dual cantilever spring comprising saidspring means, and wherein v said contacts on said spring means engagesaid contact means in the region of opposite ends of said spring means.

4. An acceleration responsive switch comprising a support member,eccentric mass means rotatably mounted in said support member, contactspring means connected to said eccentric mass, means for limiting thearc of rotation of said mass, and contact mens mounted in the path ofsaid spring means, wherein the position of the contact means isadjustable relative to said spring means to determine the magnitude ofacceleration force required to actuate said switch and wherein saidspring means extends radially in opposite directions from the axis ofrotation of said mass, and wherein one end of said spring means nor-.

mally engages a first contact of said contact means and wherein theother end of said spring means is normally spaced from a second contactof said contact means, whereby rotation of said eccentric mass developsa stress in said spring means between said axis of rotation and saidfirst-mentioned contact and causes said other end of said spring meansto engage said second-mentioned contact, thereby defining an electricalpath between said contacts.

References Cited in the file of this patent UNITED STATES PATENTS1,175,062 Johnson Mar. 14, 1916 1,256,134 Joeck Feb. 12, 1918 1,855,581Meade Apr. 26, 1932 2,731,526 Teague et al Jan. 17, 1956 2,761,031McDonald Aug. 28, 1956 2,812,398 'Mickman Nov. 5, 1957 2,966,564Cunningham Dec. 27,1960

FOREIGN PATENTS 1,200,346 France Dec. 21, 1959

1. AN ACCELERATION RESPONSIVE ELECTRICAL SWITCH COMPRISING A SUPPORTMEMBER, A SHAFT ROTATABLY MOUNTED IN SAID SUPPORT MEMBER, AN ECCENTRICMASS SECURED TO SAID SHAFT, MEANS NORMALLY MAINTAINING SAID ECCENTRICMASS TO ONE SIDE OF SAID SHAFT RELATIVE TO THE DIRECTION OF THE FORCE OFACCELERATION TO BE MEASURED, SAID LAST-MENTIONED MEANS INCLUDING MEANSFOR LIMITING THE ARC OF ROTATION OF SAID MASS, SPRING MEANS SECURED TOSAID SHAFT AND EXTENDING RADIALLY FROM SAID SHAFT, AND CONTACT MEANSPOSITIONED IN THE PATH OF SAID SPRING MEANS TO BE ENGAGED THEREBY DURINGTHE ROTATION OF SAID MASS IN RESPONSE TO AN ACCELERATING FORCE.